Use ScopedTaskEnvironment instead of MessageLoop in google_apis unit tests.

google_apis/gaia/oauth2_access_token_fetcher_impl_unittest.cc

Index: google_apis/gaia/oauth2_access_token_fetcher_impl_unittest.cc
diff --git a/google_apis/gaia/oauth2_access_token_fetcher_impl_unittest.cc b/google_apis/gaia/oauth2_access_token_fetcher_impl_unittest.cc
index b1cae64a421a06f98e5b34e203003c07873b74e9..f62cf6be9ceedc14f3a52d989982b6abf9ea684d 100644
--- a/google_apis/gaia/oauth2_access_token_fetcher_impl_unittest.cc
+++ b/google_apis/gaia/oauth2_access_token_fetcher_impl_unittest.cc
@@ -10,6 +10,7 @@
 #include <string>
 
 #include "base/run_loop.h"
+#include "base/test/scoped_task_environment.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "build/build_config.h"
 #include "google_apis/gaia/gaia_urls.h"
@@ -124,7 +125,7 @@ class OAuth2AccessTokenFetcherImplTest : public testing::Test {
   }
 
  protected:
-  base::MessageLoop message_loop_;
+  base::test::ScopedTaskEnvironment scoped_task_environment_;
   MockUrlFetcherFactory factory_;
   MockOAuth2AccessTokenConsumer consumer_;
   scoped_refptr<net::TestURLRequestContextGetter> request_context_getter_;